From: Robert Klemme <bob.news@...>
Date: 2005-05-04T14:29:32+09:00
Subject: Re: mapping an array to a hash?


"John Carter" <john.carter@tait.co.nz> schrieb im Newsbeitrag 
news:Pine.LNX.4.61.0505041025210.25628@parore.tait.co.nz...
> On Wed, 4 May 2005, Nick Woolley wrote:
>
>> Can anyone suggest an idiomatic ruby equivalent to this perl snippet?
>>
>>  my %index = map { $_ => compute_something($_) } @files;
>
>> The best I came up with so far seems reletively clunky to me:
>>
>>  index = Hash.new()
>>  files.each {|f| index[f] = compute_something(f) }
>
> If you want mind bending and obscure, try...
>
> index = Hash.new{|hash,key| hash[key] = compute_something(key)}
>
> and then somewhere totally elsewhen in the code...
>
> files.each{|f| index[f]}

That's not really equivalent to what Nick requested and it's more clunky 
also.

I prefer a solution with - guess what - #inject, but Hash[] does work, too:

>> a = [1,2,3]
=> [1, 2, 3]

>> a.inject({}) {|h,i| h[i]=i+10; h}
=> {1=>11, 2=>12, 3=>13}

>> Hash[ *a.map{|i| [i,i+10]}.flatten ]
=> {1=>11, 2=>12, 3=>13}

Kind regards

    robert